The objective of this proposed study is to develop and evaluate the immunodiagnostic method for an early detection of prostatic cancer. Prostatic acid phosphatase and ribonuclease are to be investigated in depth. These enzymes will be purified to homogeneity from human cancerous prostatic tissues and prostatic fluids with established methodologies. Specific immune sera are then raised with the purified enzymes in small animals (rabbits or goats). The sensitive immunochemical techniques (solid-phase fluorescent non-isotopic immunoassay for acid phosphatase, radioimmunoassay and enzyme-linked immunoassay for ribonuclease) will be developed utilizing the purified enzymes and their specific antiserum for measurements of minute amounts of enzymes in serum. Patients with cancer of the prostate and other tumors as well as controls will be evaluated. The ultimate goal of this proposal is to detect, by means of immunodiagnosis, the early, localized and treatable prostatic tumor.